Low pressure alarm assembly



Dec. 21, 1965 N. FENGER ETAL LOW PRESSURE ALARM ASSEMBLY Filed NOV. 21, 1963 INVENTORS NICHOLAS FENGER and JAMES R. FENGER ATTOR N E Y United States Patent 3,224,409 LOW PRESSURE ALARM AdSEMBLY Nicholas Fenger and .larnes it. Fenger, Northfield, Ohio,

assignors to Fluid Power, lno, Hudson, Ohio, a corporation of Ghio Filed Nov. 21, 1963, Ser. No. 325,381 5 Claims. (Cl. 11670) This invention relates to a low pressure alarm assembly forming a part of an automatically operated valve means communicating with a duct conveying pressurized fluid, and more particularly to improvements in a low pressure alarm assembly which emits an audible signal when the pressue of the fluid in the duct falls to a predetermined level.

The present low pressure alarm assembly finds particular utility in a self-contained compressed air breathing apparatus wherein it warns the user that the supply of air has been depleted to the point where only sufficient air remains for the user to exit from an area which is deficient in oxygen or which contains toxic fumes. It should be understood, however, that the present low pressure alarm assembly finds equal utility when used in other gas systems where an alarm is required or desired.

An overall object of the present invention is to provide an improved low pressure alarm assembly.

Another object of the present invention is to provide an improved low pressure alarm assembly which employs the pressurized fluid being sensed as a power source and therefore does not require an extrinsic power source such as an electric circuit.

Still another object of this invention is to provide an improved low pressure alarm assembly having a signal device actuating member which is slidable into and out of engagement with a sealing member thereby insuring a positive seal and minimizing the possibility of failure.

A further object of the present invention is to provide an improved low pressure alarm assembly having a minimum number of parts which undergo a minimum of wear thereby prolonging the life of the alarm assembly.

According to the present invention, an improved low pressure alarm assembly is provided which forms an integral part of an automatically operated valve means adapted to be inserted into a duct conveying pressurized air, as for example, in a self-contained compressed air breathing apparatus. The valve means is so arranged whereby it discharges pressurized fluid from the duct when the pressure of the fluid in the duct falls to a predetermined level.

The present low pressure alarm assembly is activated by the pressurized fluid discharged by the valve means and includes a signal device which produces a signal audible within a distance of about fifteen feet. Means is provided for repeatedly activating the signal device to produce a plurality of audible signals thereby insuring that the wearer of the breathing apparatus will become aware of the depleted air supply.

The means for activating the signal device receives its motive power from the pressurized fluid being sensed and therefore is self-actuating. That is to say, it does not require an extrinsic source of power. More particularly, the means for actuating the signal device comprises a striker member having at one end thereof a rod member which is slideable into and out of engagement with an annular sealing member provided in a valve opening. The rod member functions as a piston which is forced out of engagement with the sealing member by means of the force provided by the built-up pressure of the fluid from the duct. Upon the disengagement of the rod member from the sealing member, a portion of the fluid is exhausted through the valve opening to immediately reduce the pressure of the fluid. A spring member acting on the striker member, forces the rod member back into engagement with the sealing member whereupon the pressure of the fluid is permitted to build up again to subsequently act on the rod member to repeat the above-described cycle. It should be noted that the cycle described occurs very rapidly and is repeated so that audible signals are produced in rapid succession.

The above and other objects and advantages of the present invention will become apparent from the following detailed description by reference to the accompanying drawings, in which:

FIGURE 1 is a view schematically illustrating a compressed air breathing apparatus employing the low pressure alarm assembly of the present invention; and

FIG. 2 is a cross-sectional view, taken along the line II-II of FIG. 1, illustrating the internal construction of the present low pressure alarm assembly.

Referring now to FIG. 1, there is schematically illustrated a compressed air breathing apparatus generally designated by the numeral It). In general, the breathing apparatus comprises a pair of cylinders 12 which, in this instance, contain compressed air, and a duct 14 which conveys the compressed air to a face mask 16. Inserted in the duct 14 is an on-off valve 18; a T-fitting 20 having a low pressure alarm 22 connected thereto; and a demand regulator 24.

The cylinders 12 normally contain about twenty-seven cubic fee of air at pressure of 2250 p.s.i. This supply of air is sufiicient for thirty minutes of service under conditions of moderate exertion. The demand regulator 24 is of the type wherein minimum resistance is encountered during inhalation, but is positive closing during exhalation to conserve the supply of air. The demand regulater 2d normally will fail open thereby insuring a continued supply of air at all times.

The valve it; normally is of the on-ofi type. Therefore, the low pressure alarm 22 is at all times exposed to the total pressure of the fluid in the cylinders 12. The low pressure alarm 22 may be set for actuation when the fluid pressure in the duct 14 falls to any desired pressure in the range of 500 to 200 p.s.i. At this time, the low pressure alarm 22 will emit a series of audible signals notifying the wearer that the supply of air has been depleted to the point where only sufficient air remains for him to exit from the area.

Referring now to FIG. 2, the low pressure alarm 22 comprises a sealing end 26 and an alarm-emitting end 28. The sealing end 26 comprises a body portion 343 having a first bore 3, a second bore 36 of larger diameter and an enlarged bore 38 at the end thereof. A piston dtl is positioned within the body portion 3i? and has a reduced diameter end 42 adapted to fit in the first bore 34 and a larger diameter end 44 adapted to fit in the second bore 36. The piston 44 is slideable axially of the body portion 39 and is provided with a first seal 4-6 in the reduced diameter end 42 which seals against the wall of the first bore 34 and a second seal 48 in the larger diameter end 44 which seals against the Wall of the second bore 36. At the juncture of the first bore 34 and the second bore 36, there is provided an annular passageway Si? which communicates with a bleed port 52 provided in the body portion of the sealing end 26. Hence, should any one of the seals 46, 48 fail, the pressurized fluid will be conveyed to the bleed port and will not effect operation of the alarm-emitting end 28 prematurely.

The piston also is provided with a longitudinal passageway 54 which communicates with radial passageways 56 positioned downstream of the seal 46. The longitudinal passageway 54 communicates with the pressurized fluid in the duct (not shown) as indicated by the arrow 58. The reduced diameter end 42 of the piston 'has an extreme end portion 42a whose diameter is less than the diameter of the first bore 34. Thus, an annular passageway 45 is provided which communicates with the radial passageways 56. The pressurized air is conveyed through the longitudinal and radial passageways 54, 56 to the annular passageway 45 and thence to a small chamber 60 wherein the pressurized fluid acts against the end of the piston 40. A first disc member 62 is provided with a valve seat 64 which normally is engaged with a piston seat 66 to seal the small chamber 60.

As can be seen, the piston 40 is provided at its other end with a radial flange 68. A spring member 70 surrounds the piston 40 and is engaged at one end with a shoulder 72 and at the other end with the radial flange 68. Hence, the spring member 70 is adapted to urge the piston 40 away from the valve seat 64. It should be noted that the piston 40 is a differential piston in that the pressure of the fluid entering the enlarged bore 38 acts against the larger lower end of the piston 40 and is balanced by the force of the spring member 70 and the force provided by the pressurized fluid acting on the smaller upper end of the piston 40. Thus, when the pressure of the fluid in the duct 14 (see FIG. 1) falls to a predetermined level, for example 200 p.s.i., the piston 40 will be caused to move away from the valve seat 64 thereby permitting pressurized fluid to flow through a bleed aperture 74 provided in a second disc member '76. Thus, the sealing end 26 comprises an automatically operated valve means which discharges pressurized fluid from the duct 14 when the pressure of the fluid in the duct falls to a predetermined level.

The alarm-emitting end 28 of the low pressure alarm 22, is connected to the opposite end of the body portion 30 wherein there is provided a partially threaded second enlarged bore 78. The alarm-emitting mechanism comprises a cup-shaped member which is engaged with a third disc member 82 and cooperates therewith to form an expansion chamber 84 into which the sealing end 26 or valve means introduces the pressurized fluid. An annular disc member 86 is engaged with the cup-shaped member 80 and cooperates therewith to form an annular groove 88 in which a sealing element 90 is positioned. The sealing element 90 preferably comprises an O-ring of suitable diameter and made from rubber or the like. The cup-shaped member 80 and the annular disc member 86 are provided with central apertures 92 which are axially aligned and define a valve opening 94. The sealing member 90 preferably is positioned centrally of the length of the valve opening 94. An annular spacer member 95 abuts the annular disc member 86 while an externally threaded member 96 is inserted into the second enlarged bore 78 and serves to clamp the aforementioned elements between the lower end of the member 96 and a shoulder 97 at the bottom of the second enlarged bore 78.

A striker member 98 is provided which comprises a central portion 100, a first end portion 102 extending from one side of the central portion 100 and a second end portion 104 extending from the opposite side of the central portion 100. The first end portion 102 is positioned within the valve opening 94 and is engaged with the sealing element 90. The second end portion 104 extends upwardly through a central bore 106 provided in the externally threaded member 96 and includes a pin member 108 extending axially from the end thereof.

A signal device 110 comprising a cup-shaped bell member is fitted over the externally threaded member 96 and is provided with a central opening 112 through which the pin member 108 extends. A flanged conduit 114 is placed over the signal member 110 and fasteners 116 are employed to secure the signal device 110 and the flanged conduit to the externally threaded member 96. The flanged conduit 114 is axially aligned with the central opening 112 in the signal device 110 and serves to discharge the pressurized fluid to the atmosphere.

A second spring member 118 surrounds the second end portion 104 of the striker member 98 and serves to bias the first end portion 102 into engagement with the sealing element 90. The first end portion 102 preferably is circular in shape and includes a tapered end 120 for easy insertion into the sealing element 90. It should be noted that the striker member is adapted to undergo reciprocal movement between the valve opening 94 and the signal device 110 whereby the first end portion 102 is moved into and out of engagement with the sealing element 90.

In order for the signal device 110 to emit an audible alarm, the pressure of the fluid in the duct 14 must fall to a predetermined low pressure. When this occurs, the piston 40 is caused to move away from the valve seat 64 thereby permitting pressurized fluid to flow into the expansion chamber 84 by way of the bleed aperture 74.

As the pressure of the fluid in the expansion cham ber 84 increases, a force will be applied to the first end portion 102. When this force exceeds the opposing force provided by the second spring member 118, the striker member 98 will be caused to move axially toward and into engagement with the signal device 110. However, when the striker member 98 has moved into engagement with the signal device 110, the first end portion 102 will be spaced from the sealing element 90 whereby a portion of the fluid in the expansion chamber 84 is discharged to the atmosphere thereby reducing the pressure of the fluid in the expansion chamber. At this time, the second spring member 118 will force the striker member 98 back toward the valve opening 94 so that the first end portion 102 again is engaged with the sealing element 90. Hence, the expansion chamber 84 is sealed so that the pressure of the fluid may increase again.

The striker member 98 thus reciprocates between a first position wherein the first end portion 102 is engaged with the sealing element 90 to a second position wherein the striker member engages the signal device 110 to produce an audible signal and wherein the first end portion 102 is spaced from the sealing element 90. It should be noted that above-described cycle of operation occurs very rapidly and is repeated. Therefore, audible signals are created in rapid succession. Furthermore, although the first end portion 102 is spaced from sealing element 90 when in the second position, it is still engaged in the central aperture 92 of the annular disc member 88. Still further, the pin member 108 of the second end portion 104 always is engaged in the central opening 112 of the signal device 110. Hence, the striker member 104 is guided as it reciprocates between the valve opening 94 and the signal device 110, i.e., its movement is restricted to a path substantially coincident with the central axis of the central bore 106 of the externally threaded member 96.

It is also important to note that the first end portion 102 slides on the sealing element 90. The sealing element 90, then, undergoes a very slight deformation each time the first end portion 102 is inserted and withdrawn. Consequently, the sealing element 90 is subject to very little wear thereby prolonging its useful life. Still further, the present construction provides a positive seal for the expansion chamber which is one problem associated with the alarms heretofore available.

Although the present invention has been shown in connection with one specific embodiment, it will readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the present invention.

I claim as my invention:

1. In a low pressure warning alarm comprising a casing having one end adapted for connection to a source of pressurized fluids and a longitudinal passageway therethrough which communicates with the source, a reciprocating plunger having a first end and a second end, said plunger extending through said longitudinal passageway in sealing engagement therewith, spring means interposed between said first end and said casing for biasing said plunger against the pressure exerted by the pressurized fluids on said first end, conduit means extending through said plunger for exhausting fluids from said second end of said plunger into said longitudinal passageway, a first transverse wall sealing said longitudinal passageway and provided with an opening therethrough, and means carried by said second end of said plunger for sealing said opening, the force of said spring urging said sealing means out of engagement with said opening when the pressure of the source falls below a preselected level whereby pressurized fluids are discharged through said opening into said longitudinal passageway, the improvement comprising: a second transverse wall sealing said longitudinal passageway and provided with a longitudinal valve opening, said second tranverse wall being spaced from said first transverse wall to provide an expansion chamber therebetween into which pressurized fluids from the source are discharged, means interposed between said first transverse wall and said second transverse wall for metering the flow of fluids into said expansion chamber, a beater disposed within said longitudinal passageway, said beater having a first end portion extending through and engaged with said sealing element and a second end portion spaced from said first end portion, means positioned for actuation by said second end portion of said beater for emitting a signal, and means engaged with said beater for urging said first end portion into sealing engagement with said sealing element, said beater being movable cyclically between a seated position under the force of said urging means and an unseated position under the force exerted by fluids accumulated in said expansion chamber, said beater actuating said signal emitting means when in said unseated position.

2. The improvement of claim 1 including means for guiding said heater along a straight line reciprocal path of travel axially of said longitudinal passageway, said first end portion of said beater undergoing reciprocal sliding movement into and out engagement with said sealing element.

3. In a low pressure warning alarm comprising a casing having one end adapted for connection to a source of pressurized fluids and a longitudinal passageway there through which communicates with the source, a reciprocating plunger having a first end and a second end, said plunger extending through said longitudinal passageway in sealing engagement therewith, spring means interposed between said first end and said casing for biasing said plunger against the pressure exerted by the fluids on said first end, conduit means extending through said plunger for exhausting fluids from said second end of said plunger into said longitudinal passageway, a first transverse wall sealing said longitudinal passageway and provided with an opening therethrough, and means carried by said by said second end of said plunger for sealing said opening, the force of said spring urging said gasket out of engagement with the opening when the pressure of the source falls below a preselected level whereby pressurized fluids are discharged through said opening into said longitudinal passageway, the improvement comprising: a second transverse wall sealing said passageway and being provided with a longitudinal valve opening therethrough, said second transverse wall being longitudinally spaced from said first transverse wall to provide an expansion chamber therebetween in which pressurized fluids from the source are discharged, means disposed between said first transverse wall and said second transverse wall for metering the flow of fluids into said expansion chamber, an annular sealing element disposed within said valve opening, a signal emitting device on the opposite end of said casing, a heater disposed within said longitudinal passageway, said beater having a cylindrical first end portion extending through and peripherally engaged with said annular sealing element and a second end portion spaced from said signal emitting device, said cylindrical first end portion having a transverse face exposed to the interior of said expansion chamber, and means engaged with said beater for biasing said heater toward said transverse wall, said beater being movable cyclically between a seated position under the force of said biasing means and an unseated position under the force exerted on said transverse face by fluids accumulated within said expansion chamber, said beater actuating said signal emitting device when in said unseated position.

4. In a low pressure warning alarm comprising a casing having one end adapted for connection to a source of pressurized fluids and a longitudinal passageway therethrough which communicates with the source, and means carried at the opposite end of said casing for emitting a signal, the improvement comprising: first and second transverse walls sealing said passageway and being spaced apart to provide an expansion chamber therebetween, said first transverse wall having an opening through which fluids from the source flow into said expansion chamber, said second transverse wall having a valve opening through which fluids accumulated in said expansion chamber flow from said expansion chamber into that portion of said passageway downstream of said second transverse wall, a sealing element disposed in said valve opening, a beater positioned within said passageway downstream of said second transverse wall, said beater having a first end portion extending through and engaged with said sealing element and a second end portion positioned to actuate said signal emitting means, means engaged with said beater and said casing for urging said first end portion into sealing engagement with said sealing element, and means interposed between said first and second transverse walls for metering the flow of fluids into said expansion chamber, said metering means comprising a plate having a bleed port therein which permits fluids to flow into said expansion chamber at a flow rate which is less than the flow rate at which fluids flow from said expansion chamber out through said valve opening, said heater being movable cyclically between a seated position by the force of said urging means wherein said first end portion engages said sealing element to seal said valve opening and an unseated position by the force exerted on said first end portion by fluids accumulated in said expansion chamber wherein said second end portion actuates said signal emitting means and wherein said first end portion is spaced from said sealing element to discharge a portion of the fluids accumulated in said expansion chamber and thereby reduce the fluid pressure within said expansion chamber.

5. In a low pressure warning alarm comprising a casing having one end adapted for connection to a source of pressurized fluids and a longitudinal passageway there through which communicates with the source, a reciprocating plunger having a first end and a second end, said plunger extending through said longitudinal passageway in sealing engagement therewith, spring means interposed between said first end and said casing for biasing said plunger against the pressure exerted by the pressurized fluids on said first end, conduit means extending through said plunger for exhausting fluids from said second end of said plunger into said longitudinal passageway, a first transverse wall sealing said longitudinal passageway and provided with an opening therethrough, and means carried by said second end of said plunger for sealing said opening, the force of said spring means urging said gasket out of engagement with said opening when the pressure of the source falls below a preselected level whereby pressurized fluids are discharged through said opening into said longitudinal passageway, the improvement comprising: a second transverse wall sealing said longitudinal passageway and provided with a longitudinal valve opening therethrough, said second transverse wall being longitudinally spaced from said first transverse wall to provide an expansion chamber therebetween into which pressurized fluids from the source are discharged, means disposed between said first transverse wall and said second transverse wall for metering the flow of fluids into said expansion chamber, means carried at the opposite end of said casing for emitting a signal, a beater interposed between said second transverse wall and said signal emitting means, said beater having a first end portion extending through said valve opening and a second end portion positioned to actuate said sign-a1 emitting means, said first end portion and said valve opening having adjacent outer and inner surfaces respectively, a sealing element interposed between said surfaces to seal said valve opening, said sealing element being stationary with respect to one of said surfaces and being slideably engaged with the other of said surfaces, and means engaged with said beater for biasing said beater toward said second transverse wall, said heater being movable cyclically between a seated position under the force of said biasing means and an unseated position under the force exerted by fluids accumulated within said expansion chamber, said beater actuating said signal device when in said unseated position.

References Cited by the Examiner UNITED STATES PATENTS 1,929,019 10/1933 Ehn 11625 2,468,483 4/1949 Chambers et al. 11667 2,831,607 4/ 1958 Berndt 222-3 2,892,436 6/1959 Hay 1 l667 3,056,378 10/1962 Simmonds 116-70 3,131,667 5/1964 Sajeck 11670 LOUIS J. CAPOZI, Primary Examiner 

1. IN A LOW PRESSURE WARNING ALARM COMPRISING A CASING HAVING ONE END ADAPTED FOR CONNECTION TO A SOURCE OF PRESSURIZED FLUIDS AND A LONGITUDINAL PASSAGEWAY THERETHROUGH WHICH COMMUNICATES WITH THE SOURCE, A RECIPROCATING PLUNGER HAVING A FIRST END AND A SECOND END, SAID PLUNGER EXTENDING THROUGH SAID LONGITUDINAL PASSAGEWAY IN SEALING ENGAGEMENT THEREWITH, SPRING MEANS INTERPOSED BETWEEN SAID FIRST END AND SAID CASING FOR BIASING SAID PLUNGER AGAINST THE PRESSURE EXERTED BY THE PRESSURIZED FLUIDS ON SAID FIRST END, CONDUIT MEANS EXTENDING THROUGH SAID PLUNGER FOR EXHAUSTING FLUIDS FROM SAID SECOND END OF SAID PLUNGER INTO SAID LONGITUDINAL PASSAGEWAY, A FIRST TRANSVERSE WALL SEALING SAID LONGITUDINAL PASSAGEWAY AND PROVIDED WITH AN OPENING THERETHROUGH, AND MEANS CARRIED BY SAID SECOND END OF SAID PLUNGER FOR SEALING SAID OPENING, THE FORCE OF SAID SPRING URGING SAID SEALING MEANS OUT OF ENGAGEMENT WITH SAID OPENING WHEN THE PRESSURE OF THE SOURCE FALLS BELOW A PRESELECTED LEVEL WHEREBY PRESSURIZED FLUIDS ARE DISCHARGED THROUGH SAID OPENING INTO SAID LONGITUDINAL PASSAGEWAY, THE IMPROVEMENT COMPRISING: A SECOND TRANSVERSE WALL SEALING SAID LONGITUDINAL PASSAGEWAY AND PROVIDED WITH A LONGITUDINAL VALVE OPENING, SAID SECOND TRANSVERSE WALL BEING SPACED FROM SAID FIRST TRANSVERSE WALL TO PROVIDE AN EXPANSION CHAMBER THEREBETWEEN INTO WHICH PRESSURIZED FLUIDS FROM THE SOURCE ARE DISCHARGED, MEANS INTERPOSED BETWEEN SAID FIRST TRANSVERSE WALL AND SAID SECOND TRANSVERSE WALL FOR METERING THE FLOW OF FLUIDS INTO SAID EXPANSION CHAMBER, A BEATER DISPOSED WITHIN SAID LONGITUDINAL PASSAGEWAY, SAID BEATER HAVING A FIRST END PORTION EXTENDING THROUGH AND ENGAGED WITH SAID SEALING ELEMENT AND A SECOND END PORTION SPACED FROM SAID FIRST END PORTION, MEANS POSITIONED FOR ACTUATION BY SAID SECOND END PORTION OF SAID BEATER FOR EMITTING A SIGNAL, AND MEANS ENGAGED WITH SAID BEATER FOR URGING SAID FIRST END PORTION INTO SEALING ENGAGEMENT WITH SAID SEALING ELEMENT, SAID BEATER BEING MOVABLE CYCLICALLY BETWEEN A SEATED POSITION UNDER THE FORCE OF SAID URGING MEANS AND AN UNSEATED POSITION UNDER THE FORCE EXERTED BY FLUIDS ACCUMULATED IN SAID EXPANSION CHAMBER, SAID BEATER ACTUATING SAID SIGNAL EMITTING MEANS WHEN IN SAID UNSEATED POSITION. 